To provide a method of manufacturing a pneumatic tire capable of exactly reducing trapped air without a cotton yarn placed between sheet-like members for dispersing air.

Since a carcass member 5 having a plurality of grooves 5b mounted on both surfaces in a thickness direction is used, it is possible to reduce the trapped air exactly by dispersing air existing between the carcass member 5 and other sheet-like members through each groove 5b. In this case since it is not necessary to use the cotton yarn for dispersing air as in the prior art, neither the separation due to the cotton yarn (foreign substance) nor the trapped air due to gasification of moisture absorbed by the cotton yarn during vulcanization occurs. Since the process of placing the cotton yarn is omitted, it is advantageous that the productivity is not reduced. In addition since each groove 5b extends perpendicularly to the circumference, air can be discharged from the end of each groove 5b and the trapped air can be more effectively reduced.